Thermal interface materials nowadays have low heat conductivity that is inefficient to dissipate heat generated by electronics.
Generally, metals are used as the materials of heat sinks to dissipate heat, but it increase the cost of device.
Electronics have evolved very fast in recent years into smaller sizes, faster processing speed, so do devices become more compact with high capability. Due to this evolution, the heat dissipation of electronics gradually emerges as a serious problem, since density of generated heat is higher in a smaller size of device. Moreover, there are less space to accommodate heat spreaders and dissipaters. It is well known that electronic devices often crash under high temperature. Therefore, there is an urgent need for efficient heat dissipation for electronics.
Materials for heat dissipation in electronics need to be electrical insulate to prevent short circuit. Hexagonal boron nitride (hBN) has been widely used on this purpose.
Hexagonal boron nitride (hBN) has a 2D layer structure similar to graphite. hBN has very high thermal conductivity (400 W/mK) along basal plane, and its electronic insulate property makes it different from graphene. Together with hBN's excellent thermal, chemical stability, and electronic insulation, it is a promising material for heat dissipation and spreading in electron.
U.S. Pat. No. 6,054,520 disclosed hBN as fillers to make a heat dissipation sheet. The resulting silicone rubber composition had a low thermal resistance of 0.18° C./W.
US patent No. 20070259211 also disclosed a heat spreaders made of hBN. The extraction process decreased the amount of binder, which lead the spreader to have a thermal conductivity of 48 W/mK.
Besides heat spreaders, hBN has also been used as heat dissipation pastes, CN patent No. 104220533 disclosed a paste composition made of hBN, aluminum oxides and resins. Aluminum oxides increase the strength of coating, and the resulting paste has a thermal conductivity of 10 W/mK on the vertical direction.
Another patent invents a composition of hBN paste and applications such as printed circuit board (PCB). Patent CN 103087471 A disclosed 8 wt % BN filler was used, and such PCB shown a 3.43 W/mK thermal conductivity.
Patent US 2014/0020933A1 taught thermal conductivity of PCB shown a sharp increase when the composition is larger than 45 wt % BN, and reached max value of 15 W/mK at ca. 70 wt % BN in PCB substrate.
Although hBN can increase the thermal conductivity of a substrate or interlayer, the heat dissipation ability is still not high enough due to other additives such as adhesives and metal oxides.
In general, another heat dissipation component such as heat skin is attached to the heat conductive layer. For example, CN patent No. 203424617 disclosed a structure in which a metal fin is attached to heat spreader to enhance the heat dissipation.
However, heat skin made of metals is not only heavy but also increases the cost. It is also questionable whether such structure is beneficial to heat dissipation.
In fact, many heat sources in electronics generated from circuit elements or components such as LED filament or board, semiconductors chip or device, RF high power PCB, and so on.
Let heat dissipation materials contact heat source directly is the most efficient way to remove heat away.
However, metal or conductive heat dissipation coating cannot directly contact with such heat source because of short circuit issue for electronic conductive circuit elements or components.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.